Revisiting the valence-band and core-level photoemission spectra of NiO

TL;DR

This study re-examines NiO's valence and core-level electronic structures using advanced photoemission spectroscopy, revealing the Zhang-Rice doublet bound state as the lowest energy feature, consistent with theoretical models.

Contribution

It provides a detailed analysis combining experimental PES data with a configuration-interaction model, confirming the nature of the low-energy states in NiO.

Findings

Enhanced spectral weight of the lowest energy state in bulk-sensitive core-level PES

Agreement between experimental spectra and the configuration-interaction model including bound state screening

Identification of the lowest energy state as the Zhang-Rice doublet bound state

Abstract

We have re-examined the valence-band (VB) and core-level electronic structure of NiO by means of hard and soft x-ray photoemission spectroscopy (PES). The spectral weight of the lowest energy state found to be enhanced in the bulk sensitive Ni 2p core-level PES. A configuration-interaction model including the bound state screening has shown significant agreement with the core-level spectra, and the off and on-resonance VB spectra. These results identify the lowest energy state in core-level and VB-PES as the Zhang-Rice doublet bound state, consistent with the spin-fermion model and recent ab initio calculation with dynamical mean-field theory (LDA + DMFT).